This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The BTB domain is a protein-protein interaction domain that is present in all eukaryotes. Many BTB-domain-containing proteins in human cells are adaptors for ubiquitin ligases. As a ubiquitin ligase adaptor protein, the BTB protein bridges the catalytic RING protein to the protein that is targeted for ubiquitination. In yeast Yil001w fits the description of a BTB ubiquitin ligase adaptor. We found that Yil001W interacts with a cullin, Cul3, in a small Y2H screen. We are interested in finding more binding partners for Yil001w to try to fit the putative ubiquitin ligase into a cellular pathway.